CN112201281A

CN112201281A - Fluorinated ether compound, lubricant for magnetic recording medium, and magnetic recording medium

Info

Publication number: CN112201281A
Application number: CN202011204515.5A
Authority: CN
Inventors: 福本直也; 柳生大辅; 山口裕太; 植竹祥子; 加藤刚; 富田浩幸; 宫坂隆太; 室伏克己
Original assignee: Showa Denko KK
Current assignee: Lishennoco Co ltd; Resonac Holdings Corp
Priority date: 2016-08-10
Filing date: 2017-08-07
Publication date: 2021-01-08
Anticipated expiration: 2037-08-07
Also published as: CN107731245A; JP6804893B2; JP2018024614A; US10803898B2; CN112201281B; CN107731245B; US20180047419A1

Abstract

The present invention relates to a fluorine-containing ether compound represented by the following formula (1). R¹‑CH₂‑R²‑CH₂‑R³(1) (in the formula (1), R¹R is a terminal group comprising 2 or more polar groups, each of which is bonded to a different carbon atom, and carbon atoms to which the polar groups are bonded to each other via a linking group comprising a carbon atom to which a polar group is not bonded, and²comprising a perfluoropolyether chain represented by the following formula (3), R³Is hydroxy or R¹。)‑(CF₂)_y‑1‑O‑((CF₂)_yO)_z‑(CF₂)_y‑1- (3) (in the formula (3), y represents an integer of 2-4, and z represents an integer of 1-30).

Description

Fluorinated ether compound, lubricant for magnetic recording medium, and magnetic recording medium

The invention of the present application is a divisional application having application number 201710665166.9, entitled fluorochemical ether compound, lubricant for magnetic recording medium, and having application date of 2017, 8 and 7.

Technical Field

The present invention relates to a fluorinated ether compound suitable for use as a lubricant for magnetic recording media.

The present application claims priority to japanese patent application No. 2016-158134, filed on 10.8.2016, the contents of which are incorporated herein.

Background

In order to increase the recording density of a magnetic recording and reproducing apparatus, development of a magnetic recording medium suitable for a high recording density has been carried out.

Conventionally, magnetic recording media include products in which a recording layer is formed on a substrate and a protective layer such as carbon is formed on the recording layer. The protective layer protects information recorded on the recording layer and improves the slidability of the magnetic head. However, the durability of the magnetic recording medium cannot be sufficiently obtained only by providing the protective layer on the recording layer. Therefore, a lubricant is usually applied to the surface of the protective layer to form a lubricating layer.

As a lubricant used for forming a lubricating layer of a magnetic recording medium, for example, a lubricant containing CF₂The fluorine-based polymer having the repeating structure of (1) has a polar group such as a hydroxyl group at the terminal thereof (see, for example, patent documents 1 to 3).

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4632144

Patent document 2: japanese patent laid-open publication No. 2013-163667

Patent document 3: japanese patent No. 5613916

Disclosure of Invention

Problems to be solved by the invention

In a magnetic recording/reproducing apparatus, it is required to further reduce the floating amount of a magnetic head. Therefore, the thickness of the lubricating layer in the magnetic recording medium is required to be further reduced.

However, when the thickness of the lubricating layer is reduced, the adhesion between the lubricating layer and the protective layer covering the surface of the protective layer may be insufficient, and the fluorine-containing ether compound in the lubricating layer may adhere to the magnetic head as a foreign substance (smear up).

The present invention has been made in view of the above circumstances, and an object thereof is to provide a fluorinated ether compound which can be suitably used as a material for a lubricant for a magnetic recording medium, which can form a lubricating layer having good adhesion to a protective layer and can suppress adhesion.

Further, another object of the present invention is to provide a lubricant for magnetic recording media, which contains the fluorinated ether compound of the present invention.

Another object of the present invention is to provide a magnetic recording medium having a lubricating layer using the fluorinated ether compound of the present invention.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems.

As a result, the present inventors have found that a fluorinated ether compound in which an organic terminal group having 3 or more carbon atoms, in which 2 or more polar groups are contained and each polar group is bonded to a different carbon atom, are disposed at least one end of a rigid perfluoropolyether (hereinafter, sometimes referred to as "PFPE") chain, and the carbon atoms to which the polar groups are bonded to each other via a linking group containing a carbon atom to which no polar group is bonded, can be considered to be a compound having a fluorinated ether structure.

That is, the present invention relates to the following matters.

[1] A fluorine-containing ether compound represented by the following formula (1).

R¹-CH₂-R²-CH₂-R³ (1)

(in the formula (1), R¹An organic terminal group having 3 or more carbon atoms, wherein the organic terminal group having 3 or more carbon atoms contains 2 or more polar groups, each of the polar groups is bonded to a different carbon atom, the carbon atoms bonded to the polar groups are bonded to each other through a linking group containing a carbon atom to which no polar group is bonded, and R is²Comprising a perfluoropolyether chain represented by the following formula (3), R³Is hydroxy or R¹。)

-(CF₂)_y-1-O-((CF₂)_yO)_z-(CF₂)_y-1- (3)

(in the formula (3), y represents an integer of 2-4, and z represents an integer of 1-30.)

[2] A fluorine-containing ether compound represented by the following formula (2).

R¹-CH₂-R²-CH₂-R¹ (2)

(in the formula (2), R¹An organic terminal group having 3 or more carbon atoms, wherein the organic terminal group having 3 or more carbon atoms contains 2 or more polar groups, each of the polar groups is bonded to a different carbon atom, the carbon atoms bonded to the polar groups are bonded to each other through a linking group containing a carbon atom to which no polar group is bonded, and R is²Comprising a perfluoropolyether chain represented by the following formula (3). )

-(CF₂)_y-1-O-((CF₂)_yO)_z-(CF₂)_y-1- (3)

[3]According to [1]Or [2]]The fluorine-containing ether compound wherein R¹The polar group contained in (1) is a hydroxyl group.

[4]According to [1]～[3]The fluorine-containing ether compound according to any one of the above, wherein R is the same as R¹Having an ether bond (-O-).

[5]According to [1]～[4]The fluorine-containing ether compound according to any one of the above, wherein R is the same as R¹Is a terminal group of the following formula (4).

(in the formula (4), x represents an integer of 1-3.)

[6] The fluorine-containing ether compound according to any one of [1] and [3] to [5], wherein the compound in the formula (1) is represented by the following formula (5).

(in the formula (5), m represents an integer of 1-11.)

[7] The fluorine-containing ether compound according to any one of [1] and [3] to [5], wherein the compound in the formula (1) is represented by the following formula (6).

(in the formula (6), n represents an integer of 1 to 7.)

[8] The fluorine-containing ether compound according to any one of [1] and [3] to [5], wherein the compound in the formula (1) is represented by the following formula (7).

(in the formula (7), n represents an integer of 1 to 7.)

[9] The fluorine-containing ether compound according to any one of [2] to [5], wherein the compound of the formula (2) is represented by the following formula (8).

(in the formula (8), m represents an integer of 1 to 11.)

[10] The fluorine-containing ether compound according to any one of [2] to [5], wherein the compound of the formula (2) is represented by the following formula (9).

(in the formula (9), n represents an integer of 1 to 7.)

[11] The fluorine-containing ether compound according to any one of [2] to [5], wherein the compound of the formula (2) is represented by the following formula (10).

(in the formula (10), n represents an integer of 1-7.)

[12] The fluorine-containing ether compound according to any one of [1] and [3] to [5], wherein the compound in the formula (1) is represented by the following formula (11).

(in the formula (11), l represents an integer of 1 to 15.)

[13] The fluorine-containing ether compound according to any one of [1] and [3] to [5], wherein the compound in the formula (1) is represented by the following formula (12).

(in the formula (12), m represents an integer of 1-11.)

[14] The fluorine-containing ether compound according to any one of [1] and [3] to [5], wherein the compound in the formula (1) is represented by the following formula (13).

(in the formula (13), m represents an integer of 1-11.)

[15] The fluorine-containing ether compound according to any one of [2] to [5], wherein the compound of the formula (2) is represented by the following formula (14).

(in the formula (14), l represents an integer of 1 to 15.)

[16] The fluorine-containing ether compound according to any one of [2] to [5], wherein the compound of the formula (2) is represented by the following formula (15).

(in the formula (15), m represents an integer of 1-11.)

[17] The fluorine-containing ether compound according to any one of [2] to [5], wherein the compound of the formula (2) is represented by the following formula (16).

(in the formula (16), m represents an integer of 1-11.)

[18] The fluorine-containing ether compound according to any one of [1] to [17], wherein the number average molecular weight is in the range of 800 to 10000.

[19] A lubricant for a magnetic recording medium, comprising the fluorine-containing ether compound according to any one of [1] to [18 ].

[20] A magnetic recording medium comprising a substrate and, disposed thereon in this order, at least a magnetic layer, a protective layer and a lubricating layer, wherein the lubricating layer contains the fluorine-containing ether compound according to any one of [1] to [18 ].

[21] The magnetic recording medium according to [20], wherein the average film thickness of the lubricating layer is 0.5nm to 3 nm.

ADVANTAGEOUS EFFECTS OF INVENTION

The fluorine-containing ether compound of the present invention is a compound represented by the above formula (1), and is suitable as a material for a lubricant for a magnetic recording medium.

Since the lubricant for magnetic recording media of the present invention contains the fluorine-containing ether compound of the present invention, a lubricating layer having good adhesion to the protective layer and capable of suppressing adhesion can be formed.

The magnetic recording medium of the present invention has excellent durability because it has a lubricating layer that has good adhesion to the protective layer and can suppress adhesion.

Drawings

FIG. 1 is a schematic cross-sectional view showing one embodiment of a magnetic recording medium of the present invention.

Description of the reference numerals

10. magnetic recording medium, 11. substrate, 12. adhesion layer, 13. soft magnetic layer, 14. 1. base layer, 15. 2. base layer, 16. magnetic layer, 17. protective layer, 18. lubricant layer.

Detailed Description

The fluorinated ether compound, the lubricant for magnetic recording media, and the magnetic recording medium of the present invention will be described in detail below. The present invention is not limited to the embodiments described below.

[ fluorine-containing ether Compound ]

The fluorine-containing ether compound of the present embodiment is represented by the following formula (1).

R¹-CH₂-R²-CH₂-R³ (1)

(in the formula (1), R¹Is an organic terminal group having 3 or more carbon atoms, wherein the number of the organic terminal groups having 3 or more carbon atoms is 2In the above polar groups, each polar group is bonded to a different carbon atom, the carbon atoms to which the polar groups are bonded to each other via a linking group comprising carbon atoms to which polar groups are not bonded, R²Comprising a perfluoropolyether chain represented by the following formula (3), R³Is hydroxy or R¹。)

-(CF₂)_y-1-O-((CF₂)_yO)_z-(CF₂)_y-1- (3)

Here, the reason why a lubricant for a magnetic recording medium (hereinafter, sometimes simply referred to as "lubricant") containing the fluorine-containing ether compound of the present embodiment is used to form a lubricating layer on a protective layer of a magnetic recording medium, and the lubricant layer can be coated with a high coverage ratio on the surface of the protective layer and has excellent adhesion to the protective layer will be described.

The fluorine-containing ether compound of the present embodiment is represented by the formula (1) below, wherein R is²One end of the perfluoropolyether chain (hereinafter, sometimes abbreviated as "PFPE chain") is provided with R¹The terminal group represented by (A) is provided with R at the other terminal³The terminal group indicated. R¹In the lubricating layer containing the fluorine-containing ether compound of the present embodiment, the polar groups of 2 or more contained in the terminal groups are in close contact with the protective layer. R²The PFPE chain shown in the drawing not only covers the surface of the protective layer in the lubricating layer containing the fluorine-containing ether compound of the present embodiment, but also reduces the frictional force between the magnetic head and the protective layer. Further, the lubricating layer containing the fluorine-containing ether compound of the present embodiment contains R of the PFPE chain represented by formula (3) having a repeating unit having rigidity formed by a linear fluoroalkyl ether group²By R¹And R³The polar group is adhered (adsorbed) to the protective layer.

Thus, the PFPE chains may form a ring structure on the protective layer. As a result, the lubricant layer has good adhesion to the protective layer.

In addition, R¹In the terminal group represented by (a), 2 or more polar groups contained in the terminal group are bonded to different carbon atoms, and the carbon atoms to which the polar groups are bonded to each other via a linking group containing a carbon atom to which a polar group is not bonded. Having R¹The fluorine-containing ether compound having a terminal group represented by (a) is less likely to aggregate than a fluorine-containing ether compound having a terminal group in which carbon atoms bonded to polar groups are bonded to each other. Therefore, the lubricating layer containing the fluorine-containing ether compound of the present embodiment can prevent the fluorine-containing ether compound present without adhering (adsorbing) to the protective layer from aggregating and adhering as foreign matter (stain) to the magnetic head, thereby suppressing adhesion. Further, since the fluorine-containing ether compounds are less likely to aggregate with each other, the fluorine-containing ether compounds in the lubricating layer are easily disposed in a state of spreading and extending in the in-plane direction on the protective layer.

Therefore, by using the lubricant containing the above-mentioned fluorine-containing ether compound, a lubricating layer which can cover the surface of the protective layer with a high coverage ratio and has good wear resistance can be formed even when the thickness is reduced.

In addition, for R¹The terminal group represented here is a group in which carbon atoms to which polar groups are bonded to each other via a linking group containing carbon atoms to which polar groups are not bonded. Therefore, when the protective layer to which the lubricant is applied is formed of carbon or carbon containing nitrogen, R is formed¹The polar groups of 2 or more are easily oriented in the same direction with respect to the surface of the protective layer, and the polar groups are easily adhered to the surface of the protective layer in a three-dimensional arrangement. Therefore, in the case where the protective layer is formed of carbon or carbon containing nitrogen, the lubricating layer containing the fluorine-containing ether compound of the present embodiment has further excellent adhesion to the protective layer.

In the fluorine-containing ether compound represented by the formula (1), R¹An organic terminal group having 3 or more carbon atoms, wherein the organic terminal group having 3 or more carbon atoms contains 2 or more polar groups, each of the polar groups is bonded to a different carbon atom, and the carbon atoms to which the polar groups are bonded are separated from each other by a carbon atom containing a polar group which is not bondedThe linking group is bonded.

R in the formula (1)¹The amount of the fluorine-containing ether compound is appropriately selected depending on the performance required for the lubricant containing the fluorine-containing ether compound.

As R¹Examples of the polar group in (3) include a hydroxyl group, a carboxyl group, an amino group, and an aminocarboxyl group. R is a fluorine-containing ether compound for obtaining a lubricating layer having good adhesion to the protective layer¹The polar group in (1) is preferably a hydroxyl group. In addition, R is¹The polar group in (1) does not include an ether bond (-O-).

R¹The number of the polar groups in (1) is 2 or more, preferably 2 to 4. R¹When the number of the polar groups in (1) is large, the polar groups become difficult to face the protective layer due to steric hindrance. Thus, R¹The number of polar groups in (1) is most preferably 2.

R¹The 2 or more polar groups in (b) may be all different, or may be partially or entirely the same.

R¹The linking group in (4) is not particularly limited, and may be appropriately selected depending on the performance required for the lubricant containing the fluorine-containing ether compound, and the like. Specifically, the alkylene group has 1 to 4 carbon atoms such as a methylene group, an ethylene group, and a propylene group. These alkylene groups may be linked via an ether bond.

R¹Preferably having an ether linkage (-O-). R¹The ether linkage in (b) is preferably contained in the linking group.

R¹The terminal group represented by the following formula (4) is preferred. The terminal group represented by formula (4) contributes to improvement of adhesion between the protective layer coated with the lubricant containing the fluorine-containing ether compound of the present embodiment and the lubricating layer formed by coating the lubricant.

(in the formula (4), x represents an integer of 1-3.)

In the formula (4), when x is an integer of 1 to 3, R in the formula (4)²Pendant and terminal hydroxyl groupsThe distance therebetween becomes appropriate. As a result, a lubricating layer in which foreign matter (stain) is further less likely to be generated can be formed.

In the fluorine-containing ether compound represented by the formula (1), R³Is hydroxy or R¹。

At R³In the case of a hydroxyl group, adhesion to a protective layer coated with a lubricant containing a fluorine-containing ether compound due to a hydrogen bond can be obtained similarly to the terminal hydroxyl group of formula (4), and therefore, this is preferable.

At R³Is R¹In the case of (3), it is preferable that the protective layer coated with the lubricant containing the fluorine-containing ether compound has better adhesion to the lubricating layer formed by coating the lubricant. At R³Is R¹In the case of (1), R in the fluorine-containing ether compound represented by the formula³And R¹They may be the same or different as shown in the following formula (2).

R in the formula (1)³The amount of the fluorine-containing ether compound is appropriately selected depending on the performance required for the lubricant containing the fluorine-containing ether compound.

R¹-CH₂-R²-CH₂-R¹ (2)

-(CF₂)_y-1-O-((CF₂)_yO)_z-(CF₂)_y-1- (3)

In the formulae (1) and (2), R²Comprising a perfluoropolyether chain (PFPE chain) represented by the following formula (3). When a lubricant containing a fluorinated ether compound is applied to a protective layer to form a lubricating layer, the PFPE chain represented by formula (3) is coated on the protective layerAt the same time, the surface of the magnetic head is provided with lubricity to reduce the friction force between the magnetic head and the protective layer. The PFPE chain represented by formula (3) has higher rigidity than a structure containing a repeating unit formed of a PFPE chain other than that represented by formula (3). Therefore, the fluorine-containing ether compound of the present embodiment is a compound having a high rigidity of the main chain.

-(CF₂)_y-1-O-((CF₂)_yO)_z-(CF₂)_y-1- (3)

In the formula (3), y is an integer of 2 to 4, and z is an integer of 1 to 30. Y in the formula (3) is preferably an integer of 2 to 3. Z in the formula (3) is preferably an integer of 1 to 20, more preferably an integer of 1 to 15.

In the present embodiment, since y of formula (3) is an integer of 2 to 4 and z is an integer of 1 to 30, the number average molecular weight of the fluorine-containing ether compound is in a preferable range. In addition, since y of formula (3) is an integer of 2 to 4 and z is an integer of 1 to 30, the proportion of the number of oxygen atoms (the number of ether bonds (-O-)) to the number of carbon atoms in the PFPE chain becomes appropriate, and a fluorinated ether compound having appropriate rigidity is obtained. In addition, since y of the formula (3) is an integer of 2 to 4 and z is an integer of 1 to 30, the orientation of the polar group in the fluorinated ether compound coated on the protective layer is easily maintained by the rigidity of the PFPE chain, and the fluorinated ether compound is less likely to aggregate on the protective layer. As a result, a thin lubricating layer can be formed on the protective layer with a sufficient coverage by the fluorine-containing ether compound, and the PFPE chains can form a ring structure on the protective layer.

Specifically, the fluorine-containing ether compound of the present embodiment is preferably any of the compounds represented by the following formulae (5) to (20).

In the formulae, the numerical values of l, m, and n are arbitrary values among the integer values in the numerical range. For example, the compound represented by the following formula (17) is a compound in which n represents any of 1, 2, 3,. cndot.and 7. Therefore, the compound represented by the formula (17) is a compound in which n is at least 1 of 1 to 7, and does not mean a mixture of compounds in which n is all the values of 1 to 7. The same applies to other formulae.

(in the formula (17), n represents an integer of 1 to 7.)

(in the formula (5), m represents an integer of 1-11.)

(in the formula (6), n represents an integer of 1 to 7.)

(in the formula (7), n represents an integer of 1 to 7.)

(in the formula (18), n represents an integer of 1 to 7.)

(in the formula (8), m represents an integer of 1 to 11.)

(in the formula (9), n represents an integer of 1 to 7.)

(in the formula (10), n represents an integer of 1-7.)

(in the formula (19), m represents an integer of 1-11.)

(in the formula (11), l represents an integer of 1 to 15.)

(in the formula (12), m represents an integer of 1-11.)

(in the formula (13), m represents an integer of 1-11.)

(in the formula (20), m represents an integer of 1-11.)

(in the formula (14), l represents an integer of 1 to 15.)

(in the formula (15), m represents an integer of 1-11.)

(in the formula (16), m represents an integer of 1-11.)

When the fluorine-containing ether compound represented by the formula (1) is any of the compounds represented by the formulae (5) to (20), it is preferable that the compound is a compound which can form a lubricating layer having further excellent adhesion to the protective layer and can suppress adhesion.

Among the fluorine-containing ether compounds represented by the formulae (5) to (20), the fluorine-containing ether compounds represented by the formulae (8) to (10), (14) to (16), (18) and (20), which are the fluorine-containing ether compounds represented by the formula (2), are particularly preferable because they can form a lubricating layer having good adhesion to the protective layer.

The number average molecular weight of the fluorine-containing ether compound of the present embodiment is preferably in the range of 800 to 10000. When the number average molecular weight is 800 or more, the lubricant containing the fluorine-containing ether compound of the present embodiment is less likely to evaporate, and the lubricant is prevented from evaporating and transferring to and adhering to the magnetic head. The number average molecular weight of the fluorine-containing ether compound is more preferably 1000 or more. When the number average molecular weight is 10000 or less, the viscosity of the fluorine-containing ether compound becomes suitable, and a lubricant containing the compound is applied, whereby a thin lubricating layer can be easily formed. The number average molecular weight of the fluorine-containing ether compound is preferably 4000 or less in order to have a viscosity that is easy to handle when applied to a lubricant.

The number average molecular weight was determined by using AVANCEIII400 manufactured by ブルカー & バイオスピン¹H-NMR and¹⁹F-NMR. In the measurement of NMR (nuclear magnetic resonance), a sample was diluted in hexafluorobenzene/d-acetone (1/4(v/v)) solvent for measurement. For the¹⁹For F-NMR chemical shifts, the peak of hexafluorobenzene was defined as-164.7 ppm for¹The peak of acetone was defined as 2.2ppm based on the chemical shift of H-NMR.

"method of manufacture"

The method for producing the fluorine-containing ether compound of the present embodiment is not particularly limited, and can be produced by a conventionally known production method. The fluorine-containing ether compound of the present embodiment can be produced, for example, by the following production method.

First, R in the formula (1) is prepared²Each of both ends of the corresponding perfluoropolyether chain is provided with a hydroxymethyl group (-CH)₂OH) or a fluorine-containing compound.

Next, R in the formula (1) is used¹The resulting organic terminal group compound is substituted with a hydroxyl group of a hydroxymethyl group disposed at both ends (or one end) of the fluorine-based compound. In the manufacture of R³When the fluorine-containing ether compound having a hydroxyl group is used as the fluorine-containing ether compound, the substitution reaction is carried out by using 1 equivalent of a compound having the formula R with respect to the perfluoropolyether chain¹The resulting organic end group compound. In addition, in the manufacture of R³Is R¹When the fluorine-containing ether compound of (3) is used as the fluorine-containing ether compound, the substitution reaction is carried out by using a compound having R in an amount of 2 equivalents or more based on the perfluoropolyether chain¹The resulting organic end group compound. These substitution reactions can be carried out by a conventionally known method, and can be performed according to R in the formula (1)¹And R³The kind of the substance(s) and the like are appropriately determined. By the above method, the compound represented by formula (1) can be obtained.

The fluorine-containing ether compound of the present embodiment is a compound represented by the above formula (1). Therefore, when a lubricant containing the same is used to form a lubricating layer on a protective layer, R in the formula (1)²The PFPE chain can not only coat the surface of the protective layer, but also reduce the friction between the magnetic head and the protective layer. In addition, the lubricating layer formed using the lubricant containing the fluorine-containing ether compound of the present embodiment is formed by R¹The organic terminal group represented by (a) has 2 or more hydroxyl groups and thus exhibits excellent abrasion resistance due to intermolecular interaction.

In the fluorine-containing ether compound of the present embodiment, the PFPE chain is linked to the PFPE chain through R¹The organic terminal group shown has 2 or more polar groups bonded to the protective layer and adhered to the protective layer. Therefore, the lubricating layer is firmly connected with the protective layerAnd adhesion can be inhibited by the ground bonding.

[ Lubricant for magnetic recording Medium ]

The lubricant for a magnetic recording medium of the present embodiment contains a fluorine-containing ether compound represented by formula (1).

The lubricant of the present embodiment may be used in combination with known materials that can be used as a material of the lubricant as needed, as long as the properties of the lubricant including the fluorine-containing ether compound represented by formula (1) are not impaired.

Specific examples of the known material include FOMBLIN (registered trademark) ZDAC, FOMBLIN ZDALS, FOMBLIN AM-2001 (Solvay Solexis Co., Ltd.), and Moresco A20H (Moresco Co., Ltd.). The number average molecular weight of a known material used in combination with the lubricant of the present embodiment is preferably 1000 to 10000.

When the lubricant of the present embodiment contains a material other than the fluorine-containing ether compound represented by formula (1), the content of the fluorine-containing ether compound represented by formula (1) in the lubricant of the present embodiment is preferably 50% by mass or more, and more preferably 70% by mass or more.

Since the lubricant of the present embodiment contains the fluorine-containing ether compound represented by formula (1), even if the thickness is made thin, a lubricating layer which can coat the surface of the protective layer at a high coverage ratio and has excellent adhesion to the protective layer can be formed. Further, since the lubricant of the present embodiment contains the fluorine-containing ether compound represented by formula (1), the fluorine-containing ether compound in the lubricant layer present without adhering (adsorbing) to the protective layer is less likely to aggregate. Therefore, the fluorine-containing ether compound is prevented from being aggregated and attached to the magnetic head as foreign matter (stain), and adhesion is suppressed.

[ magnetic recording Medium ]

The magnetic recording medium 10 of the present embodiment has a structure in which an adhesion layer 12, a soft magnetic layer 13, a 1 st underlayer 14, a2 nd underlayer 15, a magnetic layer 16, a protective layer 17, and a lubricating layer 18 are provided in this order on a substrate 11.

Substrate "

As the substrate 11, for example, a nonmagnetic substrate or the like obtained by forming a film made of NiP or NiP alloy on a base made of metal or alloy material such as Al or Al alloy can be used.

As the substrate 11, a non-magnetic substrate made of a non-metal material such as glass, ceramic, silicon carbide, carbon, or resin may be used, or a non-magnetic substrate obtained by forming a film of NiP or NiP alloy on a base made of such a non-metal material may be used.

Adhesive layer "

When the adhesion layer 12 is disposed in contact with the substrate 11 and the soft magnetic layer 13 provided on the adhesion layer 12, corrosion of the substrate 11 is prevented from proceeding.

The material of the adhesion layer 12 can be appropriately selected from Cr, Cr alloy, Ti alloy, and the like, for example. The adhesion layer 12 can be formed by sputtering, for example.

"Soft magnetic layer"

The soft magnetic layer 13 preferably has a structure in which a 1 st soft magnetic film, an intermediate layer formed of a Ru film, and a2 nd soft magnetic film are sequentially stacked. That is, the soft magnetic layer 13 is preferably configured such that an intermediate layer formed of a Ru film is interposed between 2 layers of soft magnetic films, and antiferromagnetic Coupling (AFC) is bonded to the upper and lower soft magnetic films having the intermediate layer. When the soft magnetic layer 13 has a structure in which AFC is bonded, it is possible to improve resistance to an external magnetic field and resistance to a water (wide Area Track erase) phenomenon, which is a problem specific to perpendicular magnetic recording.

The 1 st and 2 nd soft magnetic films are preferably films formed of CoFe alloy. In the case where the 1 st and 2 nd soft magnetic films are films formed of CoFe alloy, a high saturation magnetic flux density Bs (1.4(T) or more) can be achieved.

In addition, it is preferable to add any of Zr, Ta, and Nb to the CoFe alloy used for the 1 st and 2 nd soft magnetic films. This promotes the amorphization of the 1 st and 2 nd soft magnetic films, improves the orientation of the 1 st underlayer (seed layer), and reduces the amount of floating of the magnetic head.

The soft magnetic layer 13 can be formed by sputtering, for example.

"layer 1 of basal"

The 1 st base layer 14 is a layer for controlling the orientation and crystal size of the 2 nd base layer 15 and the magnetic layer 16 provided thereon. The 1 st underlayer 14 is provided to increase the component of the magnetic flux generated from the magnetic head in the direction perpendicular to the substrate surface and to more firmly fix the magnetization direction of the magnetic layer 16 in the direction perpendicular to the substrate 11.

The 1 st base layer 14 is preferably a layer formed of a NiW alloy. When the 1 st underlayer 14 is a layer made of a NiW alloy, other elements such as B, Mn, Ru, Pt, Mo, and Ta may be added to the NiW alloy as necessary.

The 1 st base layer 14 can be formed by, for example, sputtering.

"No. 2 substrate layer"

The 2 nd base layer 15 is a layer in which the orientation of the magnetic layer 16 is controlled to be good. The 2 nd base layer 15 is preferably a layer formed of Ru or a Ru alloy.

The 2 nd base layer 15 may be a layer formed of 1 st layer or may be formed of a plurality of layers. When the 2 nd base layer 15 is formed of a plurality of layers, all the layers may be made of the same material, or at least one layer may be made of a different material.

The 2 nd base layer 15 can be formed by, for example, sputtering.

Magnetic layer "

The magnetic layer 16 is formed of a magnetic film having an easy magnetization axis oriented in a vertical or horizontal direction with respect to the substrate surface. The magnetic layer 16 is a layer containing Co and Pt, and may further contain an oxide, Cr, B, Cu, Ta, Zr, or the like in order to improve SNR characteristics.

Examples of the oxide contained in the magnetic layer 16 include SiO₂、SiO、Cr₂O₃、CoO、Ta₂O₃、TiO₂And the like.

The magnetic layer 16 may be composed of 1 layer or may be composed of a plurality of magnetic layers formed of materials having different compositions.

For example, the magnetic layer 16 is composed of a 1 st magnetic layer,When the 3 nd magnetic layers 2 and 3 rd magnetic layers are formed, the 1 st magnetic layer preferably has a granular structure formed of a material containing Co, Cr, Pt, and further an oxide. As the oxide contained in the 1 st magnetic layer, for example, an oxide of Cr, Si, Ta, Al, Ti, Mg, Co, or the like is preferably used. Among them, TiO is particularly suitably used₂、Cr₂O₃、SiO₂And the like. The 1 st magnetic layer is preferably formed of a composite oxide in which 2 or more oxides are added. Among them, Cr is particularly suitably used₂O₃-SiO₂、Cr₂O₃-TiO₂、SiO₂-TiO₂And the like.

The 1 st magnetic layer may contain 1 or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in addition to Co, Cr, Pt, and oxides.

By containing 1 or more of the above elements, the miniaturization of the magnetic particles can be promoted, the crystallinity and orientation can be improved, and the recording/reproducing characteristics and the thermal fluctuation characteristics suitable for high-density recording can be obtained.

The same material as that of the 1 st magnetic layer can be used for the 2 nd magnetic layer. The 2 nd magnetic layer is preferably granular in structure.

The 3 rd magnetic layer is preferably a non-granular structure formed of a material containing Co, Cr, Pt, and no oxide. The 3 rd magnetic layer may contain 1 or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, Mn in addition to Co, Cr, Pt. By including the above-described elements in addition to Co, Cr, and Pt in the 3 rd magnetic layer, it is possible to promote the miniaturization of the magnetic particles, to improve the crystallinity and orientation, and to obtain recording and reproducing characteristics and thermal fluctuation characteristics suitable for higher density recording.

In the case where the magnetic layer 16 is formed of a plurality of magnetic layers, a nonmagnetic layer is preferably provided between adjacent magnetic layers. When the magnetic layer 16 is formed of 3 layers of the 1 st magnetic layer, the 2 nd magnetic layer, and the 3 rd magnetic layer, it is preferable to provide a nonmagnetic layer between the 1 st magnetic layer and the 2 nd magnetic layer, and between the 2 nd magnetic layer and the 3 rd magnetic layer.

By providing the nonmagnetic layer between the adjacent magnetic layers with an appropriate thickness, magnetization reversal of each film becomes easy, dispersion of magnetization reversal of the entire magnetic particles can be reduced, and the S/N ratio can be further improved.

For the nonmagnetic layer provided between the adjacent magnetic layers of the magnetic layer 16, for example, Ru alloy, CoCr alloy, CoCrX1 alloy (X1 represents 1 or 2 or more elements selected from Pt, Ta, Re, Ru, Cu, Nb, Ni, Mn, Ge, Si, O, N, W, Mo, Ti, V, Zr, and B), or the like can be used as appropriate.

In the non-magnetic layer provided between adjacent magnetic layers of the magnetic layer 16, an alloy material containing an oxide, a metal nitride, or a metal carbide is preferably used. Specifically, as the oxide, for example, SiO can be used₂、Al₂O₃、Ta₂O₅、Cr₂O₃、MgO、Y₂O₃、TiO₂And the like. As the metal nitride, for example, AlN or Si can be used₃N₄TaN, CrN, etc. As the metal carbide, for example, TaC, BC, SiC, or the like can be used.

The nonmagnetic layer can be formed by sputtering, for example.

In order to achieve a higher recording density, the magnetic layer 16 is preferably a perpendicular magnetic recording magnetic layer in which the easy magnetization axis is oriented in a direction perpendicular to the substrate surface, but may be in-plane magnetic recording.

The magnetic layer 16 can be formed by any conventionally known method such as vapor deposition, ion beam sputtering, magnetron sputtering, and the like, and can be formed by sputtering in general.

Protective layer "

The protective layer 17 is a layer for protecting the magnetic layer 16. The protective layer 17 may be formed of one layer or may be formed of a plurality of layers. Examples of the material of the protective layer 17 include carbon, carbon containing nitrogen, silicon carbide, and the like.

As a film forming method of the protective layer 17, a sputtering method using a target containing carbon, a CVD (chemical vapor deposition) method using a hydrocarbon material such as ethylene or toluene, an IBD (ion beam deposition) method, or the like can be used.

Lubricating layer "

The lubricating layer 18 prevents contamination of the magnetic recording medium 10. The lubricating layer 18 also reduces the frictional force of the magnetic head of the magnetic recording and reproducing device that slides on the magnetic recording medium 10, thereby improving the durability of the magnetic recording medium 10.

As shown in fig. 1, the lubricant layer 18 is formed in contact with the protective layer 17. The lubricating layer 18 is a layer formed by applying the lubricant for a magnetic recording medium of the above-described embodiment on the protective layer 17. Therefore, the lubricating layer 18 contains the above-described fluorine-containing ether compound.

In the case where the protective layer 17 disposed below the lubricating layer 18 is formed of carbon, carbon containing nitrogen, or silicon carbide, the lubricating layer 18 is bonded to the fluorine-containing ether compound contained in the protective layer 17 with a high bonding force. As a result, the magnetic recording medium 10 can be easily obtained in which the surface of the protective layer 17 can be covered with a high coverage even if the thickness of the lubricating layer 18 is thin, and contamination of the surface of the magnetic recording medium 10 can be effectively prevented.

The average film thickness of the lubricating layer 18 is preferably set

More preferably

When the average film thickness of the lubricant layer 18 is 0.5nm or more, the lubricant layer 18 can be formed with a uniform film thickness without forming islands or nets. Therefore, the surface of the protective layer 17 can be coated with a high coverage by the lubricating layer 18. Further, by setting the average film thickness of the lubricating layer 18 to 3nm or less, the floating height of the magnetic head can be sufficiently reduced, and the recording density of the magnetic recording medium 10 can be improved.

When the surface of protective layer 17 is not covered with lubricating layer 18 at a sufficiently high coverage, the environmental substance adsorbed on the surface of magnetic recording medium 10 penetrates through the gaps of lubricating layer 18 and enters under lubricating layer 18. The environmental substance that has entered the lower layer of the lubricant layer 18 is adsorbed and bonded to the protective layer 17, and generates a contaminant. In addition, during magnetic recording and reproduction, the contaminants (agglomerated components) adhere (transfer) to the magnetic head as stains, which may damage the magnetic head or degrade the magnetic recording and reproduction characteristics of the magnetic recording and reproduction device.

Examples of the environmental substance which generates a contaminant include siloxane compounds (cyclic siloxane and linear siloxane), ionic compounds, hydrocarbons having a relatively high molecular weight such as octacosane, and plasticizers such as dioctyl phthalate. Examples of the metal ion contained in the ionic impurity include sodium ion and potassium ion. Examples of the inorganic ion contained in the ionic impurity include a chloride ion, a bromide ion, a nitrate ion, a sulfate ion, and an ammonium ion. Examples of the organic ions contained in the ionic impurities include oxalic acid ions and formic acid ions.

Method for forming lubricating layer "

For forming the lubricating layer 18, for example, a method of preparing a magnetic recording medium in the middle of production in which layers up to the protective layer 17 are formed on the substrate 11, and coating the protective layer 17 with a lubricating layer forming solution is given.

The lubricating layer forming solution can be obtained by the following method: the lubricant for magnetic recording media of the above-described embodiment is diluted with a solvent as necessary, and adjusted to a viscosity and a concentration suitable for the coating method.

Examples of the solvent usable in the solution for forming a lubricant layer include fluorine-based solvents such as バートレル (registered trademark) XF (trade name, manufactured by mitsui デュポンフロロケミカル).

The method of applying the solution for forming the lubricating layer is not particularly limited, and examples thereof include spin coating, dipping, and the like.

In the case of using the dipping method, for example, the following methods can be used. First, the substrate 11 on which the layers up to the protective layer 17 are formed is immersed in a solution for forming a lubricating layer contained in an immersion tank of an immersion coating apparatus. Next, the substrate 11 is lifted up from the immersion tank at a predetermined speed. Thereby, the lubricating layer forming solution is applied to the surface of the substrate 11 on the protective layer 17.

By the dipping method, the lubricant layer forming solution can be uniformly applied to the surface of the protective layer 17, and the lubricant layer 18 can be formed on the protective layer 17 with a uniform film thickness.

The magnetic recording medium 10 of the present embodiment is a product in which at least a magnetic layer 16, a protective layer 17, and a lubricating layer 18 are provided in this order on a substrate 11. In the magnetic recording medium 10 of the present embodiment, the lubricating layer 18 containing the above-described fluorine-containing ether compound is formed in contact with the protective layer 17. Even if the lubricant layer 18 is thin, the surface of the protective layer 17 is covered with a high coverage. Therefore, in the magnetic recording medium 10 of the present embodiment, environmental substances such as ionic impurities that generate contaminants are prevented from entering through the gaps in the lubricating layer 18. Therefore, the magnetic recording medium 10 of the present embodiment is a product with less contaminant substances present on the surface. Further, in the magnetic recording medium 10 of the present embodiment, the lubricant layer 18 is less likely to generate foreign matters (stains) and can suppress sticking. In addition, the lubricating layer 18 in the magnetic recording medium 10 of the present embodiment has excellent wear resistance.

[ examples ]

The present invention will be described in more detail below with reference to examples and comparative examples. The present invention is not limited to the following examples.

"example 1"

In a nitrogen atmosphere, 300mL eggplant-shaped bottle was charged with HOCH₂CF₂CF₂O(CF₂CF₂CF₂O)_n ¹CF₂CF₂CH₂Fluoropolyether (n) represented by OH¹1-7, number average molecular weight 1280, molecular weight distribution 1.2 (10g), tert-butanol (70mL), and potassium tert-butoxide (0.9g) to make a mixture. The resulting mixture was stirred for 1 hour while being heated to 70 ℃.

Then, bromopropylene oxide (3.1g) was added dropwise to the above mixture, and the mixture was further stirred for 5 hours while being heated to 70 ℃ and cooled to 25 ℃. Then, a fluorine-based solvent (trade name: アサヒクリン (registered trademark) AK-225, manufactured by Asahi glass company) was added to the eggplant type bottle, and the reaction product was washed with water to recover an organic phase in the eggplant type bottle. Next, sodium sulfate was added to the recovered organic phase, followed by dehydration and filtration through a filter. Next, the solvent was distilled off from the filtrate using an evaporator. Then, the residue was separated by column chromatography.

By the above-mentioned steps, colorless transparent liquid compound 1(5.0g) represented by formula (a) was obtained.

Of the Compound 1 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝2.60(1H)，2.77(1H)，3.12(1H)，3.57(1H)，3.95(1H)，4.00(2H)，4.12(2H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-130.00～-129.00(12F),-127.48(2F),-124.33(2F),-86.42(4F),-84.00～-83.00(24F)

(in the formula (A), n¹Represents an integer of 1 to 7. )

Compound 1(1g) represented by formula (A) and tert-butanol (10mL) were charged into a 100mL eggplant-shaped flask under a nitrogen atmosphere, and the mixture was stirred until it became homogeneous. Next, ethylene glycol (0.8mL) and potassium tert-butoxide (0.2g) were added to the above mixture, and the mixture was stirred for 9 hours while being heated to 70 ℃ and then cooled to 25 ℃.

Then, a fluorine-based solvent (trade name: アサヒクリン (registered trademark) AK-225, manufactured by Asahi glass company) was added to the eggplant type bottle, and the reaction product was washed with water, recovered, dehydrated, filtered, and the residue was separated by column chromatography in the same manner as the compound 1 represented by the formula (A).

Through the above-described steps, colorless transparent liquid compound 2(0.7g) represented by formula (B) was obtained. The compound is n¹1-7 of a mixture of compounds.

Of the Compound 2 obtained¹H-NMR and¹⁹F-NMR measurement, the structure was identified by the following results。

¹H-NMR (acetone-D)₆)：δ[ppm]＝3.30～4.10(11H)，4.12(2H)

(in the formula (B), n¹Represents an integer of 1 to 7. )

"example 2"

Instead of HOCH₂CF₂CF₂O(CF₂CF₂CF₂O)_n ¹CF₂CF₂CH₂Fluoropolyether (n) represented by OH¹1-7 mixture, number average molecular weight 1280, molecular weight distribution 1.2), using HOCH₂CF₂CF₂O(CF₂CF₂CF₂O)_m ¹CF₂CF₂CH₂Fluoropolyether (m) represented by OH¹Except for 1 to 11 mixtures having a number average molecular weight of 1800 and a molecular weight distribution of 1.2), colorless transparent liquid compound 3(0.7g) represented by formula (C) was obtained in the same manner as compound 2 represented by formula (B) in example 1. The compound is m¹1-11 in weight percent.

Of the Compound 3 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝1.79(2H)，3.30～4.10.(11H)，4.12(2H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-130.00～-129.00(18F),-127.48(2F),-124.33(2F),-86.42(4F),-84.00～-83.00(36F)

(in the formula (C), m¹Represents an integer of 1 to 11. )

"example 3"

A colorless transparent liquid compound 4 represented by the following formula (D) (0.7g) was obtained in the same manner as in example 1 except that 1, 3-propanediol was used instead of ethylene glycol and compound 2 represented by the formula (B). The compound is n¹1-7 of a mixture of compounds.

Of the Compound 4 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝1.79(2H)，3.30～4.10.(11H)，4.12(2H)

(in the formula (D), n¹Represents an integer of 1 to 7. )

"example 4"

A colorless transparent liquid compound 5 represented by the following formula (E) was obtained in the same manner as in example 1 except that 1, 4-butanediol was used instead of ethylene glycol and compound 2 represented by the formula (B) (0.7 g). The compound is n¹1-7 of a mixture of compounds.

Of the Compound 5 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝1.61(2H),1.71(2H)，3.30～4.10.(11H)，4.12(2H)

(in the formula (E), n¹Represents an integer of 1 to 7. )

"example 5"

The same operation as for the compound 1 represented by the formula (a) in example 1 was carried out except that the amount of propylene bromide to be added was changed to 6.2g, thereby obtaining a colorless transparent liquid compound 6 represented by the following formula (F) (6.0 g).

Of the Compound 6 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝2.60(2H)，2.77(2H)，3.12(2H)，3.57(2H)，3.98(2H)，4.12(4H)¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-130.00～-129.00(12F),-124.33(4F),-86.42(4F),-84.00～-83.00(24F)

(in the formula (F), n¹Represents an integer of 1 to 7. )

Under a nitrogen atmosphere, compound 6(1g) represented by formula (F) and tert-butanol (10mL) were charged into a 300mL eggplant-shaped flask, and stirred until homogeneous to obtain a mixture. Next, ethylene glycol (1.1mL) and potassium tert-butoxide (0.2g) were added to the above mixture, and the mixture was stirred for 9 hours while being heated to 70 ℃ and then cooled to 25 ℃.

Then, a fluorine-based solvent (trade name: アサヒクリン (registered trademark) AK-225, manufactured by Asahi glass company) was added to the eggplant type bottle, and the reaction product was washed with water, recovered, dehydrated, filtered, and the residue was separated by column chromatography in the same manner as the compound 1 represented by the formula (A). Through the above-described steps, colorless transparent liquid compound 7(0.7G) represented by formula (G) was obtained. The compound is n¹1-7 of a mixture of compounds.

Of the Compound 7 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝3.30～4.10(18H)，4.12(4H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-130.00～-129.00(12F),-124.33(4F),-86.42(4F),-84.00～-83.00(24F)

(in the formula (G), n¹Represents an integer of 1 to 7. )

"example 6"

Instead of HOCH₂CF₂CF₂O(CF₂CF₂CF₂O)_n ¹CF₂CF₂CH₂Fluoropolyether (n) represented by OH¹1-7 mixture, number average molecular weight 1280, molecular weight distribution 1.2), using HOCH₂CF₂CF₂O(CF₂CF₂CF₂O)_m ¹CF₂CF₂CH₂Fluoropolyether (m) represented by OH¹Except for 1 to 11 mixtures having a number average molecular weight of 1800 and a molecular weight distribution of 1.2), colorless transparent liquid compound 8(0.7G) represented by the following formula (H) was obtained in the same manner as in compound 7 represented by formula (G) in example 5. The compound is m¹1-11 in weight percent.

Of the Compound 8 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝3.30～4.10(18H)，4.12(4H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-130.00～-129.00(18F),-124.33(4F),-86.42(4F),-84.00～-83.00(36F)

(in the formula (H), m¹Represents an integer of 1 to 11. )

"example 7"

In the same manner as in example 5 except for using 1, 3-propanediol instead of ethylene glycol and using compound 7 represented by formula (G), compound 9(0.7G) represented by formula (I) was obtained as a colorless transparent liquid. The compound is n¹1-7 of a mixture of compounds.

Of the Compound 9 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝1.79(4H)，3.30～4.10.(18H)，4.12(4H)

(in the formula (I), n¹Represents an integer of 1 to 7. )

"example 8"

A colorless transparent liquid compound 10(0.7G) represented by the following formula (J) was obtained in the same manner as in example 5 except that 1, 4-butanediol was used instead of ethylene glycol and compound 7 represented by the formula (G). The compound is n¹1-7 of a mixture of compounds.

Of the Compound 10 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝1.61(4H)，1.71(4H)，3.30～4.10.(18H)，4.12(4H)

(in the formula (J), n¹Represents an integer of 1 to 7. )

"example 9"

HOCH in example 1₂CF₂CF₂O(CF₂CF₂CF₂O)_n ¹CF₂CF₂CH₂Replacement of fluoropolyether represented by OH by HOCH₂CF₂O(CF₂CF₂O)_m ¹CF₂CH₂Fluoropolyether (m) represented by OH¹Except for 1 to 11 mixtures, number average molecular weight 1330 and molecular weight distribution 1.1), colorless transparent liquid compound 11(5.2g) represented by formula (K) was obtained in the same manner as compound 1 represented by formula (a).

Of the Compound 11 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝2.60(1H)，2.77(1H)，3.12(1H)，3.57(1H)，3.88(1H)，3.93(2H)，4.08(2H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-89.50～-88.50(40F)，-81.25(2F)，-78.50(2F)

(in the formula (K), m¹Represents an integer of 1 to 11. )

A colorless transparent liquid compound 12 represented by the following formula (L) (0.7g) was obtained in the same manner as the compound 2 represented by the formula (B) except that the compound 1 represented by the formula (a) in example 1 was replaced with the compound 11 represented by the formula (K). The compound is m¹1-11 in weight percent.

Of the Compound 12 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝3.30～4.10(11H)，4.08(2H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-89.50～-88.50(40F)，-81.25(2F),-78.50(2F)

(in the formula (L), m¹Represents an integer of 1 to 11. )

"example 10"

Instead of HOCH₂CF₂CF₂O(CF₂CF₂CF₂O)_n ¹CF₂CF₂CH₂Fluoropolyether represented by OH, using HOCH₂CF₂O(CF₂CF₂O)_l ¹CF₂CH₂Fluoropolyether (l) represented by OH¹Except for 1 to 15 mixtures having a number average molecular weight of 1800 and a molecular weight distribution of 1.2), colorless transparent liquid compound 13(0.7g) represented by the following formula (M) was obtained in the same manner as in compound 3 represented by formula (C) in example 2. The compound is¹1-15 of a mixture of compounds.

Of the Compound 13 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝3.30～4.10(11H)，4.08(2H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-89.50～-88.50(56F)，-81.25(2F)，-78.50(2F)

(in the formula (M), l¹Represents an integer of 1 to 15. )

"example 11"

The formula (A) in example 1 is shown in TableIn the same manner as in example 1 and compound 2 represented by formula (B), except that compound 1 shown was replaced with compound 11 represented by formula (K) and 1, 3-propanediol was used instead of ethylene glycol, compound 14(0.7g) was obtained as a colorless transparent liquid compound represented by formula (N). The compound is m¹1-11 in weight percent.

Of the Compound 14 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝1.79(2H)，3.30～4.10(11H)，4.08(2H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-89.50～-88.50(40F),-81.25(2F),-78.50(2F)

(in the formula (N), m¹Represents an integer of 1 to 11. )

"example 12"

A colorless, transparent, liquid compound 15 represented by the following formula (O) was obtained in the same manner as in the compound 2 represented by the formula (B) in example 1 except that the compound 1 represented by the formula (a) in example 1 was replaced with the compound 11 represented by the formula (K) and 1, 4-butanediol was used in place of ethylene glycol (0.7 g). The compound is m¹1-11 in weight percent.

Of the Compound 15 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝1.61(2H)，1.71(2H)，3.30～4.10(11H)，4.08(2H)

(in the formula (O), m¹Represents an integer of 1 to 11. )

"example 13"

HOCH in example 1₂CF₂CF₂O(CF₂CF₂CF₂O)_n ¹CF₂CF₂CH₂Replacement of fluoropolyether represented by OH by HOCH₂CF₂O(CF₂CF₂O)_m ¹CF₂CH₂In the same manner as in the case of the compound 1 represented by the formula (a), except that fluoropolyether represented by OH (m: a mixture of 1 to 11, number average molecular weight 1330, molecular weight distribution 1.1) was added dropwise in an amount of 5.9g, the compound 16 represented by the following formula (P) was obtained as a colorless transparent liquid (5.9 g).

Of the Compound 16 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝2.60(2H)，2.77(2H)，3.12(2H)，3.57(2H)，3.88(2H)，4.08(4H)¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-89.50～-88.50(40F)，-78.50(4F)

(in the formula (P), m¹Represents an integer of 1 to 11. )

A colorless transparent liquid compound 17 represented by the following formula (Q) (0.7G) was obtained in the same manner as the compound 7 represented by the formula (G) except that the compound 6 represented by the formula (F) in example 5 was replaced with the compound 16 represented by the formula (P). The compound is m¹1-11 in weight percent.

Of the Compound 17 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝3.30～4.10(18H)，4.08(4H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-89.50～-88.50(40F),-78.50(4F)

(in the formula (Q), m¹Represents an integer of 1 to 11. )

"example 14"

Instead of HOCH₂CF₂CF₂O(CF₂CF₂CF₂O)_n ¹CF₂CF₂CH₂Fluoropolyether represented by OH, using HOCH₂CF₂O(CF₂CF₂O)_l ¹CF₂CH₂Fluoropolyether (l) represented by OH¹Except that the number-average molecular weight of the mixture was 1 to 15, and the molecular weight distribution was 1800 and 1.2), colorless transparent liquid compound 18(0.7G) represented by the following formula (R) was obtained in the same manner as in compound 7 represented by formula (G) in example 5. The compound is¹1-15 of a mixture of compounds.

Of the obtained Compound 18¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝3.30～4.10(11H)，4.08(2H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-89.50～-88.50(56F),-81.25(2F),-78.50(2F)

(in the formula (R), l¹Represents an integer of 1 to 15. )

"example 15"

A compound represented by the formula (G) in example 5, except that the compound 6 represented by the formula (F) in example 5 was replaced with the compound 16 represented by the formula (P), and 1, 3-propanediol was used in place of ethylene glycolThe same procedures as in substance 7 gave colorless transparent compound 19(0.7g) in a liquid state, which was represented by the following formula (S). The compound is m¹1-11 in weight percent.

Of the Compound 19 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝1.79(4H)，3.30～4.10(18H)，4.08(4H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-89.50～-88.50(40F),-78.50(4F)

(in the formula (S), m¹Represents an integer of 1 to 11. )

"example 16"

A colorless transparent liquid compound 20(0.7G) represented by the following formula (T) was obtained in the same manner as in example 5 except that the compound 6 represented by the formula (F) in example 5 was replaced with the compound 16 represented by the formula (P) and 1, 4-butanediol was used in place of ethylene glycol. The compound is m¹1-11 in weight percent.

Of the Compound 20 obtained¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝1.61(4H)，1.71(4H)，3.30～4.10(18H)，4.08(4H)

¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-89.50～-88.50(40F)，-78.50(4F)

(in the formula (T), m¹Represents an integer of 1 to 11. )

Examples 1 to 16 obtained as described aboveThe compound of (A) corresponds to the structure of formula (1) or (2), and R²The value of y in the formula (3) and R¹The value of x in the case of formula (4) is shown in Table 1.

[ Table 1]

Comparative example 1 "

Using HOCH₂CF₂O(CF₂CF₂O)_p(CF₂O)_qCF₂CH₂A fluoropolyether represented by OH (p is 1 to 7, q is 1 to 7, number average molecular weight 1300, molecular weight distribution 1.1) in place of HOCH₂CF₂CF₂O(CF₂CF₂CF₂O)_nCF₂CF₂CH₂Except for fluoropolyether represented by OH, colorless transparent liquid compound 21(0.7g) represented by the following formula (U) was obtained in the same manner as in compound 3 represented by formula (C) in example 2.

Preparation of the obtained Compound 21¹H-NMR and¹⁹F-NMR measurement was carried out, and the structure was identified by the following results.

¹H-NMR (acetone-D)₆)：δ[ppm]＝3.30～4.50(13H)¹⁹F-NMR (acetone-D)₆)：δ[ppm]＝-91.15～-88.51(24F)，-83.21(1F),-81.22(1F),-80.61(1F),-78.75(1F),-55.65～-51.59(12F)

(in the formula (U), p represents an integer of 1-7, and q represents an integer of 1-7.)

Comparative example 2 "

Compound 22 represented by the following formula (V) was synthesized by the method described in japanese patent No. 4632144.

(in the formula (V), p represents an integer of 1-7, and q represents an integer of 1-7.)

Comparative example 3 "

Compound 23 represented by the following formula (W) was synthesized by the method described in japanese patent No. 4632144.

(in the formula (W), r represents an integer of 1-11, and s represents an integer of 1-11.)

Using the above¹H-NMR and¹⁹F-NMR measurement of the compounds of examples 1 to 16 and comparative examples 1 to 3 obtained as described above were determined for the number average molecular weight. The results are shown in Table 2.

Next, a solution for forming a lubricating layer was prepared by the following method using the compounds obtained in examples 1 to 16 and comparative examples 1 to 3. Then, the lubricating layer of the magnetic recording medium was formed by the following method using the obtained solution for forming a lubricating layer, and the magnetic recording media of examples 1 to 16 and comparative examples 1 to 3 were obtained.

Solution for forming lubricant layer "

The compounds obtained in examples 1 to 16 and comparative examples 1 to 3 were each dissolved in バートレル (registered trademark) XF (trade name, manufactured by Mitsui デュポンフロロケミカル) as a fluorine-based solvent so that the film thickness when the coating was applied to the protective layer was set to be

The solution was diluted with バートレル to prepare a lubricant layer forming solution.

Magnetic recording medium "

A magnetic recording medium was prepared in which an adhesion layer, a soft magnetic layer, a 1 st underlayer, a2 nd underlayer, a magnetic layer, and a protective layer were provided in this order on a substrate having a diameter of 65 mm. The protective layer is formed of carbon.

The solutions for forming a lubricating layer according to examples 1 to 16 and comparative examples 1 to 3 were applied to the protective layer of the magnetic recording medium on which the layers up to the protective layer were formed by the dipping method. The dipping method was carried out under conditions of a dipping speed of 10mm/sec, a dipping time of 30sec, and a lifting speed of 1.2 mm/sec.

Then, the magnetic recording medium coated with the lubricating layer forming solution was placed in a thermostatic bath at 120 ℃ and heated for 10 minutes to remove the solvent in the lubricating layer forming solution, thereby forming a lubricating layer on the protective layer to obtain a magnetic recording medium.

The thickness of the lubricating layer of the magnetic recording media of examples 1 to 16 and comparative examples 1 to 3 obtained as described above was measured by FT-IR (trade name: Nicolet iS50, manufactured by Thermo Fisher Scientific Co., Ltd.). The results are shown in Table 2.

The magnetic recording media of examples 1 to 16 and comparative examples 1 to 3 were evaluated by measuring the bond rate and performing adhesion inhibition tests by the following methods. The results are shown in Table 2.

(measurement of adhesion between lubricating layer and protective layer (bond percentage))

The magnetic recording medium on which the lubricating layer was formed was immersed in バートレル as a solvent for 10 minutes and then washed. The magnetic recording medium was immersed in the solvent at a speed of 10mm/sec and pulled up at a speed of 1.2 mm/sec.

Then, the film thickness of the lubricating layer was measured by the same method as the measurement of the film thickness of the lubricating layer performed before the washing.

Then, the film thickness of the lubricant layer before washing was denoted as a, the film thickness of the lubricant layer after washing (after solvent immersion) was denoted as B, and the bonding ratio (bond ratio) of the lubricant was calculated from the ratio of a to B ((B/a) × 100 (%)). Using the calculated bond ratio, the adhesion between the lubricant layer and the protective layer was evaluated according to the following criteria.

Evaluation of adhesion (bond Rate) "

O: the bond rate is 50% or more

X: the bond rate is less than 50 percent

(adhesion inhibition test)

The magnetic recording medium and the magnetic head were mounted on a rotating frame (spun), and the magnetic head was floated at a fixed point for 10 minutes at normal temperature under reduced pressure (about 250 torr). Then, the surface of the magnetic head facing the magnetic recording medium (the surface of the lubricating layer) was analyzed by an ESCA (Electron Spectroscopy for Chemical Analysis) analyzer. Then, the amount of lubricant adhering to the magnetic head was evaluated from the intensity of the peak derived from fluorine (signal intensity (a.u.)) measured by ESCA using the criteria shown in table 3. The results are shown in Table 2.

[ Table 2]

[ Table 3]

As shown in table 2, in examples 1 to 16, the evaluation results of the adhesion (bond rate) between the lubricant layer and the protective layer and the adhesion suppression test were good. It is understood from the above that by forming a lubricating layer on the protective layer of a magnetic recording medium using a lubricant for a magnetic recording medium containing the compounds of examples 1 to 16, it is possible to obtain a lubricant having a thickness as thin as possible

And a lubricating layer which has excellent adhesion to the protective layer and is less likely to cause adhesion.

In contrast, as shown in Table 2, in comparative examples 1 to 3, the bond ratio was smaller than in examples 1 to 16. In comparative examples 1 to 3, the evaluation results of the adhesion inhibition test were x.

The above results are presumed to be due to the following reasons: since the fluorinated ether compounds used in examples 1 to 16 include the PFPE chain represented by formula (3) having a repeating unit formed of a linear fluoroalkyl ether group, the PFPE chain had rigidity and adhesion to the protective layer was improved as compared with the fluorinated ether compounds used in comparative examples 1 to 3.

In addition, as shown in Table 2, R³Is R¹Examples 5 to 8 of (formula (2))³The bond ratios were higher in examples 1 to 4 in which hydroxyl groups were used. In addition, R³Is R¹Examples 13 to 16 of (formula (2))³The bond ratios of examples 9 to 12 in which hydroxyl groups were present were higher than those of examples. From the above results, it can be seen that R is added¹Is arranged at R²Thereby further improving the adhesion.

Industrial applicability

By using the lubricant for magnetic recording media containing the fluorine-containing ether compound of the present invention, a lubricating layer which has excellent adhesion to a protective layer and is less likely to cause adhesion even when the thickness is reduced can be obtained.

Claims

1. A fluorine-containing ether compound represented by the following formula (1):

R¹-CH₂-R²-CH₂-R³ (1)

in the formula (1), R¹Is an organic end group represented by the following formula (4), R²Comprising a perfluoropolyether chain represented by the following formula (3), R³Is hydroxy or R¹，

-(CF₂)_y-1-O-((CF₂)_yO)_z-(CF₂)_y-1- (3)

In the formula (3), y is 2, z represents an integer of 1 to 30,

in the formula (4), x represents an integer of 1 to 3.

2. The fluorine-containing ether compound according to claim 1, wherein R is the same as R³Is R¹。

3. The fluorine-containing ether compound according to claim 1, wherein x in the formula (4) is an integer of 2 to 3.

4. The fluorine-containing ether compound according to claim 1, wherein the compound in the formula (1) is represented by the following formula (11):

in the formula (11), l represents an integer of 1 to 15.

5. The fluorine-containing ether compound according to claim 1, wherein the compound in the formula (1) is represented by the following formula (12):

in the formula (12), m represents an integer of 1 to 11.

6. The fluorine-containing ether compound according to claim 1, wherein the compound in the formula (1) is represented by the following formula (13):

in the formula (13), m represents an integer of 1 to 11.

7. The fluorine-containing ether compound according to claim 1, wherein the compound in the formula (1) is represented by the following formula (14):

in the formula (14), l represents an integer of 1 to 15.

8. The fluorine-containing ether compound according to claim 1, wherein the compound in the formula (1) is represented by the following formula (15):

in the formula (15), m represents an integer of 1 to 11.

9. The fluorine-containing ether compound according to claim 1, wherein the compound in the formula (1) is represented by the following formula (16):

in the formula (16), m represents an integer of 1 to 11.

10. The fluorine-containing ether compound according to claim 1, which has a number average molecular weight in the range of 800 to 10000.

11. A lubricant for a magnetic recording medium, comprising the fluorine-containing ether compound according to any one of claims 1 to 10.

12. A magnetic recording medium comprising a substrate and, disposed thereon in this order, at least a magnetic layer, a protective layer and a lubricating layer, wherein the lubricating layer contains the fluorine-containing ether compound according to any one of claims 1 to 10.

13. The magnetic recording medium according to claim 12, wherein the average film thickness of the lubricating layer is 0.5nm to 3 nm.